The invention relates to novel biologically active peptides which act as antagonists of the biological activities of bradykinin and its homologs and congeners, the pharmaceutically acceptable salts of these antagonists, and their application as therapeutic agents.
Bradykinin (BK), a nonapeptide (SEQ ID:3) (Arg.sup.1 -Pro.sup.2 -Pro.sup.3 -Gly.sup.4 -Phe.sup.5 -Ser.sup.6 -Pro.sup.7 -Phe.sup.8 -Arg.sup.9) and its physiologically important related peptides, kallidin (Lys-bradykinin) and Met-Lys-bradykinin, exhibit physiological actions which qualify them as mediators of inflammatory reactions, hypotensive states, and pain. Bradykinin is overproduced in pathological conditions such as septic (Robinson et al., Am. J. Med. 59: 61 (1975)) and hemorrhagic (Hirsch et al., J. Surg. Res. 17: 147 (1974)) shock, anaphylaxis (Collier and James, J. Physiol. 160: 15P (1966)) , arthritis (Jasani et al. , Ann. Rheum. Dis. 28: 497 (1969); Hamberg et al., Agents Actions 8: 50( 1978); Sharma et al., Arch. Int. Pharmacodyn. 262: 279 (1983)) , rhinitis (Proud et al., J. Clin. Invest. 72: 1678 (1983); Naclerio et al., Clin. Res. 33: 613A (1985)) , asthma (Christiansen et al., J. Clin. Invest. 79: 188 (1987)), inflammatory bowel disease (Zeitlin and Smith, Gut 14: 133 (1973)), and certain other conditions including acute pancreatitis, post-gastrectomy dumping syndrome, carcinoid syndrome, migraine, and hereditary angioedema (Leme, Handb. Exp. Pharmacol. 50/I: 464 (1978)). The production of bradykinin results in pain at the site of the pathological condition, and the overproduction intensifies the pain directly or via stimulation by bradykinin of the activation of the arachidonic acid pathway which produces prostaglandins and leukotrienes, more distal mediators of inflammation (Handbook of Experimental Pharmacology, Vol. 25, Springer-Verlag (1969), and Vol. 25 Supplement (1979); Stewart, in "Mediators of the Inflammatory Process," Henson and Murphy, eds., Elsevier, (1989)).
Bradykinin has been found to be produced in inflammatory reactions in the intestine, provoking contraction of smooth muscle and secretion of fluid and ions. The existence of specific bradykinin receptors in the mucosal lining of the intestine and in intestinal smooth muscle is demonstrated by Manning et al. (Nature 229: 256 (1982)), showing the influence of bradykinin in very low concentrations upon fluid and ion secretion.
The production of bradykinin and associated pain in angina has been studied and reported (Kimura et al., Amer. Heart J. 85: 635 (1973); Staszewska-Barczak et al., Cardiovasc. Res. 10: 314 (1976)). The reported action of bradykinin and prostaglandins acting in concert are the natural stimulus for excitation of the sensory receptors signalling the pain of myocardial ischemia.
Bradykinin and bradykinin-related kinins are not only produced endogenously, but may also be injected into an animal via stings or bites. It is known that insects such as hornets and wasps inject bradykinin related peptides that cause pain, swelling and inflammation.
Bradykinin and related peptides exert their actions on biological systems by combining with specific receptors on cell membranes in the affected tissues. These receptors are of two classes, designated B1 and B2. The B2 receptors require the entire bradykinin sequence for effective receptor combination and production of the biological effects, whereas the B1 receptors do not respond to intact bradykinin, but respond selectively to bradykinin lacking the carboxy-terminal arginine residue; this peptide is designated [des-Arg.sup.9 ]-bradykinin. [des-Arg.sup.9 ]-Bradykinin is produced in the body by one of the enzymes that normally destroys bradykinin, the plasma enzyme carboxypeptidase N, that removes the carboxy-terminal arginine residue. Essentially all normal physiological responses and many pathophysiological responses to bradykinin are mediated by B2 receptors, whereas in certain damaged tissues and in certain kinds of chronic inflammation, B1 receptors are induced. The currently accepted wisdom is that bradykinin antagonist drugs for treatment of chronic inflammation must have antagonist action at both B1 and B2 receptors.
The search for understanding of the mechanisms of action of bradykinin, which is essential for the development of useful tools for diagnostic use, and for the development of therapeutic agents aimed at alleviating the intense pain and other symptoms caused by the overproduction of bradykinin, was severely hindered by the lack of specific sequence-related competitive antagonists of bradykinin until the discovery of the first effective bradykinin antagonists by Vavrek and Stewart in 1985 (Vavrek et al., Peptides 6:161-164 (1985); U.S. Pat. No. 4,693,993). In these early antagonists, the proline residue at position 7 of bradykinin was replaced by a D-aromatic amino acid residue, usually D-phenylalanine or D-thienylalanine. Subsequently, many modifications of the original bradykinin antagonists have been described (reviewed by J. M. Stewart and R. J. Vavrek in R. M. Burch, ed., "Bradykinin Antagonists," Pergamon, 1990), but most effective antagonists have had an aromatic amino acid residue at positions 5 and 8 and a D-aromatic residue at position 7. In certain antagonists, positions 5, 7, and 8 are occupied by aliphatic amino acid residues (J. M. Stewart, et al. in "Peptides 1992," C. H. Schneider and A. N. Eberle, eds., ESCOM, Leiden, 1993, pp 691-692).
Antagonists for bradykinin B1 receptors are obtained by replacing the phenylalanine residue at position 8 of [des-Arg.sup.9 ]-bradykinin by an aliphatic amino acid, such as leucine. Thus, [Leu.sup.8, des-Arg.sup.9 ]-bradykinin and Lys-[Leu.sup.8, des-Arg.sup.9 ]-bradykinin are effective B1 receptor antagonists. All of the bradykinin antagonists of the type described by Stewart and Vavrek, containing a D-amino acid residue at position 7, act only upon B2 receptors. In certain in vivo assays, some of these early antagonists were shown to act upon both B2 and B1 receptors, but it was demonstrated that those antagonists were substrates for carboxypeptidase N, and that the antagonist action on B1 receptors occurred only after cleavage of the antagonist to the [des-Arg.sup.9 ]analog. Newer, more potent, types of bradykinin antagonists contain residues at position 8 (such as Cpg, Oic) that block the degradative action of carboxypeptidase N; these antagonists have no action at B1 receptors. The present art of bradykinin antagonist peptides has not described any B1 antagonists that possess a carboxy-terminal arginine residue. Certain of the bradykinin antagonists described in this application that do contain the carboxy-terminal arginine residue have been found to possess high antagonist activity at both B1 and B2 receptors. This discovery runs counter to all principles generally accepted in the state of the art of bradykinin antagonists. Notwithstanding prior efforts, there remains a considerable need to provide improved B1 and B2 receptor antagonists. A main object of the present invention is to provide such receptor antagonists which include indaneglycine substituted bradykinin antagonists demonstrating B1 receptor and B2 receptor antagonist activity with high potency and broad specificity of antagonism.